The partial circuit for an NPN BJT constant current sink is shown in Figure 419. Circuit conditions and model parameter for Q1 are given below.
ICQ= 800 µA
Vt= 26 mV
Using these parameters and the values shown on the schematic, you are asked to do the following.
(a) Calculate the value for the output resistance R0 seen at the collector to ground.
(b) With RB1 equal to 100KO, calculate the value for RB2 that will produce R0 of 2.5MO.